Device for regulated heating of media in a dental handpiece

ABSTRACT

A device for regulated heating of media in a dental handpiece ( 1 ) has at least one media line ( 10 ) which can be opened via a switch ( 32 ), a heating element ( 12, 31 ) associated with the media line ( 10 ), a temperature sensor ( 13, 34 ) detecting the temperature of the medium and a regulation circuit ( 33 ) which is connected with the temperature sensor ( 13, 34 ) and controls the heating element ( 12, 31 ) in dependence upon the sensor signals. After an actuation of the switch. ( 32 ) the heating element ( 12, 31 ) is operated for a short period of time at a predetermined heating power independent of the output signal of the regulation circuit ( 33 ), in order to heat the medium as rapidly as possible to the required temperature.

[0001] The present invention relates to a device for regulated heatingof media in a dental handpiece, in particular in a dental sprayhandpiece.

[0002] Spray handpieces are put to use at dental treatment stations forvarious purposes, for example for blowing clear treatment sites in themouth of the patient or for rinsing. Thereby, as a rule, sprayhandpieces offer the possibility of delivering a water-air mixture inthe form of a spray for the cooling or cleaning of treatment sites. Forthis purpose, the handpiece has a nozzle via which water, air, or waterand air simultaneously are issued. Both media should thereby be heatedto approximately body temperature in order to cause in the patient, inwhose mouth they are put to use, no reflex or defense reactions.Normally, the heating of the individual media can also be switched offin order to deliberately deliver cold media and therewith, for exampleafter certain treatments, to test reflexes of the patient.

[0003] In order to heat the media issued by the spray handpiece to atemperature which remains as uniform as possible, it is known from EP 0525 443 A1 to adapt the heating power to the media consumption. For thispurpose, the power delivered to the heating elements is varied with theaid of a pulse packet controller, which includes a switching elementlying in the heating current circuit and actuable by a setting member,between a lower limit, which corresponds to heating being switched off,and a maximum heating power. The possibility of altering the heatingpower exists also with a handpiece known from DE 195 48 444 C1. Here, independence upon the throughflow quantity of the issued medium there isderived an electrically processable parameter with the aid of acharacteristic line stored in a controller component, which parametercorresponds to a heating power necessary for the attainment of thedesired media temperature.

[0004] Since, with the handpiece known from DE 195 48 444 C1, theheating power required to obtain a desired temperature is determinedwith the aid of a predetermined characteristic line, externalinfluences, such as for example a temperature variation of the mediummade available from an initial reservoir, can no longer be taken intoaccount. Thus, although complicated measures for exact temperatureregulation are avoided, there is however accepted through this a certaininexactitude in the temperature of the issued medium which is in the endattained.

[0005] In order to set the temperature of the medium as exactly aspossible, with a handpiece known from DE 39 01 198 A1 there are providedtemperature sensors which are arranged within the handpiece and veryclose to the exit nozzle. These temperature sensors are connected withregulating units which are likewise accommodated in the handpiece,whereby the regulating units control the heating elements in dependenceupon the sensor signals. With the aid of this regulation circuitry thetemperature of the issued media can thus be set very exactly. Since,moreover, the temperature sensors are arranged close to the outletnozzle of the handpiece, a cooling of the media on the way from theheating element to the nozzle can likewise be taken into account.

[0006] The employment of a regulation circuit for the media heating thusmakes possible a very precise setting of the media temperature; sincethe regulation however involves a certain delay effect the period oftime over which, after switching on of air and/or water, the desiredfinal temperature for the two media is attained is lengthened. Beyondthis, with a simultaneous temperature regulation of both media, energyconsumption is increased.

[0007] The object of the present invention is so to improve the knownarrangements for the heating of the media in a dental handpiece thatafter a switching on of the media these are heated as rapidly aspossible to the desired intended temperature.

[0008] This object is achieved by means of a device which has thefeatures of claim 1. The device has first at least one media line whichcan be opened by a switch, a heating element associated with the medialine, a temperature sensor which detects the temperature of the medium,and a regulation circuit. The regulation circuit is thereby connectedwith the temperature sensor and controls the heating element independence upon the sensor signals, as is already known from DE 39 01198 A1.

[0009] The solution in accordance with the invention consists in thatafter an actuation of the switch, the heating element is operated for ashort period of time at a predetermined heating power, independently ofthe output signal of the regulation circuit. Through this, the heatingis in any event switched on for a short period of time independently ofthe output signal of the regulation circuit, whereby through thesuppression of the regulation in the initial stage the medium emergingfrom the output nozzle is heated to the desired intended temperature inas short as possible time.

[0010] A further object of the present invention consists in keeping theenergy consumption of the media heating as low as possible.

[0011] In accordance with a second aspect of the present invention, thisobject is achieved in that with a device for regulated heating of airand water in a dental handpiece, in the case of a simultaneous actuationof the switches for air and for water, the heating element for the airmedia line is switched off. In the case of a spray operation of thehandpiece, only the water is thus heated, whilst the additional heatingof the air is omitted, in order not to use energy unnecessarily. Theswitching off of the air heating thereby has only an insignificanteffect on the temperature of the spray, since this is in any eventvirtually completely determined by the water temperature.

[0012] Further developments of the invention are the subject ofsubclaims.

[0013] The period of time of the above-described suppression of theheating regulation is preferably dependent upon the switch-on intervalof the switch for the media line. In the case that the regulationcircuit for the operation of the heating element switches, with the aidof transistor, an optotriac, which in turn switches a power triac forthe heating current of the heating element, this can be achieved in thatan RC member is connected to the base terminal of the transistor, whichRC member after an actuation of the switch suppresses the output signalof the regulation circuit for a short period of time. The dischargeresistor for the capacitor of the RC member now ensures that thesuppression time of the regulation is made dependent upon the switch-oninterval of the switch. The period of time for which the regulation issuppressed is thereby preferably ca. one second, whereby thissuppression of the regulation is preferably provided exclusively for theheating of the air.

[0014] The temperature sensors and the other electronic components ofthe heating device in accordance with the invention are preferablyarranged completely within the dental handpiece, in order to be able tofully exploit the advantages offered through the temperature regulation.

[0015] A further aspect of the present invention relates to the powerloss arising in the electronic components of the heating device, inparticular at the power triac for controlling the heating elements. Inorder to minimize this power loss, the loss heat arising at the powertriac for the water heating can be directly returned to the water to beheated. The return is effected with the aid of a heat exchanger elementwhich is connected to the water line and thermally coupled with thepower triac. Through this, on the one hand the energy usage of the mediaheating is optimized, on the other hand the heat discharge from thepower triac is improved, and therewith an undesired heating of thehandpiece avoided.

[0016] Below, the invention will be described in more detail withreference to the accompanying drawings. There is shown:

[0017]FIG. 1 a dental spray handpiece, with which the device inaccordance with the invention is to be put to use, in a side view;

[0018]FIG. 2 the dental spray handpiece in a part section;

[0019]FIG. 3 the main elements of the heating device in accordance withthe invention, in a perspective view;

[0020]FIG. 4a,

[0021]4 b different views of a circuit board which carries the mainelements of the heating device;

[0022]FIG. 5 the underside of the circuit board for a preferredexemplary embodiment;

[0023]FIGS. 6a-c various variants of the exemplary embodimentillustrated in FIG. 5, in section;

[0024]FIG. 7 a block circuit diagram of the heating device in accordancewith the invention.

[0025] The dental spray handpiece 1 illustrated in FIG. 1 is comprisedof an elongate grip body 2, to the rear side of which there is arrangeda media coupling 3, via which the handpiece 1 can be connected to aconventional supply hose. The media coupling 3 has for this purposeindividual connection pieces for the media air and water as well asfurther supply lines, for example for current and light.

[0026] At the forward end of the grip body 2 there is arranged a bowednozzle body 4 at the free end of which the nozzle 5 for the issue of airand/or water is located. Via the nozzle body 4, beyond this, light canalso be directed onto the site to be treated.

[0027] In the forward region of the elongate grip body 2 there arelocated on its upper side a touch panel 6 with two actuating elementsfor the media air and water. Via the actuating elements, the valve forthe corresponding media line can be opened and a switch for thecorresponding media heating can be closed. With a simultaneous actuationof both actuating elements, the media lines for air and water aresimultaneously open, so that air and water can be issued in the form ofa spray with the aid of the nozzle 5 arranged at the forward end of thenozzle body 4.

[0028]FIG. 2 shows a part of the elements arranged of the interior ofthe handpiece 1. For reasons of clarity the trip levers actuable via thetouch panel 6 for opening the media lines and switching on the mediaheatings are not illustrated, just as the electronic components of thetemperature regulation are not. The two media lines 10 and 11 for airand water run within the grip body 2 in longitudinal direction. Bothmedia lines 10 and 11 are connected at their rearward end with the mediacoupling 3. In the forward region of the media line 10 for air there islocated a heating element 12 with the aid of which the air flowingthrough the media line 10 is warmed. The heating element may be forexample a conventional heating cartridge which continues the media line10 so that the air is heated upon flowing through the heating cartridge12. In a similar manner there is also provided a corresponding heatingelement for the media line 11 for water.

[0029] In order to make possible a temperature regulation there isarranged at the forward end of the media line 10 for air a temperaturesensor 13 which measures of the temperature of the air after flowingthrough the heating element 12. This arrangement of the temperaturesensor 13 is of advantage since on the one hand measurement takes placevery close to the heating element 12 and thus an unintended burnout ofthe heating element 12 is avoided. On the other hand, the sensor 13 islocated very close to the outlet point of the medium so that a coolingof the medium along the final stretch of path up to the nozzle 5, whichcannot be avoided, remains negligibly small. A second temperature sensorfor the media line 11 for water is arranged in similar manner at theopposite side of the grip body.

[0030] The electronic components of the media heating in accordance withthe invention are arranged on an elongate base circuit board 14 which isto explained in more detail below. In this connection, FIG. 3 showsagain the main components of the device in accordance with the inventionfor the heating of the media. Thereby, one of the two trip levers 15 isalso illustrated, which upon an actuation of the corresponding actuationelement on the outside of the handpiece is pressed down, on the one handto open the valve for the corresponding media line and on the other handto activate the heating for this medium. The activation of the heatingis effected by means of a projection, projecting from the lever towardsthe interior which presses down upon a contact (not shown) located onthe base circuit board 14.

[0031] The base circuit board 14 is an injection molded circuitrycarrier, a so-called 3D-MID (molded interconnected device). Suchcircuitry carriers combine both mechanical and also electronic functionsin a single element and correspondingly offer the possibility of keepingthe dimensions of the overall device as small as possible. Through this,the installation of the complete heating device in the handpiece is madepossible. From the different views of the base circuit board 14 in FIGS.4a and 4 b it can be understood that at its underside there are providedguides 18 for the tube-shaped heating elements, so that a reliableattachment is made possible. At the forward end there are furtherlocated tube-like connection pieces 16 to which the outputs of theheating elements are connected. Within these connecting pieces 16 thereare also located the temperature sensors with the aid of which thetemperature of the media issued by the heating elements is determined.

[0032] In the rearward region of the base circuit board 14 there arearranged in the one hand the two contacts 19 and 20 which upon pressingdown of the corresponding trip lever activate the associated mediaheatings. Further, there are arranged on the upper and lower sides thefurther electronic components of the heating, generally designated bythe reference signs 21 and 22, in particular the two power triacs 22explained below, for operating the media heatings 12. The electricalconnection between the various components and contacts is establishedvia conductor lines which run on the upper and lower sides of the basecircuit board 14 and through the circuit board 14.

[0033]FIG. 5 shows a particularly preferred variant of the heatingdevice in accordance with the invention. In order to minimize the not beneglected power loss of the heating, the loss heat arising at the powertriac 22 a for the water heating is directly returned to the water to beheated. The return is effected with the aid of a heat exchanger element23 that is connected to the water line 11. Through this on the one handthe energy usage of the media heating is optimized, on the other handthe heat removal from the power triac 22 a is improved and therewith anundesired heating of the handpiece prevented. This heat return ispreferably provided solely for the water heating.

[0034] For the return of the loss heat, various variants are conceivablewhich are to be explained below with reference to the sectionedillustrations in FIGS. 6a to 6 c.

[0035] With the first variant according to FIG. 6a, the base circuitboard 14 is so shaped that the heat exchanger element 23 is fixed in itsposition and a heat exchange surface is formed between heat exchangerelement 23 and power triac 22 a. The bearing surfaces of the heatexchanger element 23 and power triac 22 a, and the region of the basecircuit board 14 lying therebetween, are provided with a metallizedlayer 24. This layer 24, which is formed analogously to conductortracks, ensures a thermal connection and thus a heat discharge from thepower triac 22 a to the heat exchanger element 23. This first variantdistinguishes itself in particular through a simple construction.

[0036] With the second variant according to FIG. 6b there is provided anadditional cooling body 25 as heat transport means, which is so shapedthat a heat exchange surface between power triac 22 a and heat exchangerelement 23 which is as great as possible is formed. The cooling body 23is placed between the base circuit board 24 on the one hand and thepower triac 22 a and the heat exchanger element 23 on the other hand andmakes possible, in comparison to the variant illustrated in FIG. 6a,improved heat conduction.

[0037] Finally, with the third variant according to FIG. 6c, the heatexchanger element 23 is formed in one piece and so configured that thepower triac 22 a can be arranged directly on this. This third variantmakes possible a further improved transfer of heat. The heat coupling ofall three variants can, finally, be further improved in that in theregion of the bearing surfaces of the power triac 22 a and of the heatexchanger element 23 there is additionally applied a heat conductingpaste.

[0038] On the basis of the block circuit diagram in FIG. 7 the manner offunctioning of the heating device in accordance with the invention is tobe explained below. Thereby, for the control and heating solely a singlesupply voltage of preferably 24 Volts AC is needed, to which allcomponents of the heating device, that is both the regulation units andalso the heating elements, are connected.

[0039] The block diagram in FIG. 7 shows a control component 30 which isresponsible overall for the activation of the heating device, and thetwo heating and regulation circuits for air and for water. Both heatingcircuits thereby consist firstly of a switch 32 or 42, which uponactuation of the corresponding actuating element on the upper side ofthe handpiece and the opening of the media valve, are closed via a triplever and therewith the corresponding media heating is switched on. Theheating elements 31 and 41 for air and for water are each operated via apower triac 36 or 46 via which the power for the two heating elements31, 41 is set. The control of the power triac 36 or 46 is effected ineach case by means of an optotriac 35 or 45 switching at zero crossings,with the aid of which a fault suppression is made possible. The controlof the optotriac 35 or 45 is effected by means of control circuits 33 or43 which control, in dependence upon the required heating power, atransistor 37 or 47, to the output of which the optotriac 35 or 45 isconnected.

[0040] The regulation circuits 33 and 43 are in each case connected witha corresponding temperature sensor 34 or 44 and generate in dependenceupon the sensor signals control signals for the respective transistors37 and 47. With the aid of these control signals the two power triacs 36and 46 are thus operated with the power required for the attainment of adesired temperature for the medium.

[0041] The media heating for air has, in comparison with the mediaheating for water, additionally also an RC member 38 which is connectedwith the base terminal of the transistor 37 and connects this with theoutput of the switch 32. Upon a closing of the switch 32—that is, upon aswitching on of the media heating for the air—the RC member 38 has theeffect that the output signals of the regulation circuit 33 aresuppressed for a short period of time and the transistor 37 is socontrolled that the heating element 31 is operated at maximum heatingpower for a short period of time. Through this it is achieved that uponan opening of the media line the air is heated rapidly to the desiredtemperature. Since the capacitor of the RC member discharges again, witha certain delay, after the opening of the switch 32, this suppressiontime for the regulation of the heating can be made dependent upon theswitch-on interval of the switch. Preferably the period of time for thesuppression of the temperature regulation of the air heating is about asecond.

[0042] A further special feature of the heating consists in that uponclosure of the switch 42 for the water media heating, an additionaltransistor 39 is so controlled that the air media heating is completelyswitched off. This has the consequence, in the case that the switchesfor air and water are simultaneously closed in order to operate thespray handpiece in spray operation, that exclusively the heating for thewater is activated and correspondingly the energy for an additionalheating of the air is saved. Since the temperature of the spray is, dueto the high thermal coefficient of the water, in any event determinedprimarily through the water temperature, the omission of the air heatinghas no substantial temperature change as a consequence, but reduces theenergy consumption of the media heating.

[0043] The present invention thus makes possible an effective and energysaving possibility for setting the temperature of the media issued froma spray handpiece to a desired value. Thereby, the device can becompletely and space-savingly integrated into a handpiece.

1. Device for regulated heating of media in a dental handpiece (1)having a) at least one media line (10) which can be opened via a switch(32), b) a heating element (12, 31) associated with the media line (10),c) a temperature sensor (13, 34) detecting the temperature of the mediumand d) a regulation circuit (33) which is connected with the temperaturesensor (13, 34) and controls the heating element (12, 31) in dependenceupon the sensor signals, characterized in that, the heating element (12,31) is, after an actuation of the switch (32), operated for a shortperiod of time at a predetermined heating power independent of theoutput signal of the regulation circuit (33).
 2. Device according toclaim 1, characterized in that, the suppression time of the regulationis dependent upon the switch-on interval of the switch (32).
 3. Deviceaccording to claim 1, characterized in that, the device has a furthermedia line (11) which can be opened by second switch (42), with whichfurther media line there are associated a second heating element (41), asecond temperature sensor (44) and a second regulation circuit (43), thesecond regulation circuit (43) controlling the second heating element(41) in principle in dependence upon the sensor signals of the secondtemperature sensor.
 4. Device according to claim 3, characterized inthat, the first media line (10) is provided for the delivery of air andthe second media line (11) for the delivery of water, wherein upon asimultaneous actuation of the two switches (32, 42) the heating element(31) for the air media line (10) is switched off.
 5. Device forregulated heating of media in a dental handpiece (1) having a media line(10) for air which can opened via a switch (32) and a media line (11)for water which can be opened via a further switch (42), there beingassociated with each media line (10, 11) in each case a heating element(12, 31; 41), a temperature sensor (13, 34; 44) detecting thetemperature of the medium and a regulation circuit (33; 34) connectedwith the corresponding temperature sensor (13, 34), and the regulationcircuits (33; 43) controlling the respective heating elements (12, 31)in dependence upon the sensor signals, characterized in that, upon asimultaneous actuation of the two switches (32, 42) the heating element(31) for the air media line (10) is switched off.
 6. Device according toclaim 5, characterized in that, after an actuation of the first switch(32) the associated heating element (12, 31) for the air media line (10)is operated for a short period of time at a predetermined heating powerindependent of the output signal of the associated regulation circuit(33).
 7. Device according to claim 6, characterized in that, thesuppression time of the regulation for the heating element (12, 31) forthe air media line (10) is dependent upon the switch-on interval of theswitch (32).
 8. Device according to claim 1 or 5, characterized in that,the regulation circuit (33) or regulation circuits (33, 43) controls viaa transistor (37, 47) an optotriac (35, 45) switching at zero crossing,which optotriac switches a power triac (36, 46) for the heating currentof the heating element (12, 31, 41) concerned.
 9. Device according toclaim 8, characterized in that, there is connected to the base terminalof the transistor (37) for the air heating an RC member (38) which afteran actuation of the first switch (32) for the air media heatingsuppresses the output signal of the regulation circuit (33) for a shortperiod of time.
 10. Device according to claim 1 or 5, characterized inthat, the temperature sensor or sensors (34, 44) are arranged directlyin the associated media line (10, 11).
 11. Device according to claim 8,characterized in that, there is provided in the media line (11) forwater an heat exchanger element (23) which for returning the loss heatarising at the power triac (23 a, 46) for the water heating is thermallycoupled therewith.
 12. Device according to claim 11, characterized inthat, the power triac (22 a, 46) for the water heating and the heatexchanger element (23) are arranged on a common circuit board (14) andconnected with one another via a metallized layer.
 13. Device accordingto claim 11, characterized in that, the power triac (22 a, 46) for thewater heating and the heat exchanger element (23) are arranged on acommon cooling body (25).
 14. Device according to claim 11,characterized in that, the heat exchanger element (23) forms a bearingsurface for the power triac (22 a, 46) for the water heating.
 15. Deviceaccording to claim 11, characterized in that, in the region of thebearing surfaces for the power triac (22 a, 46) for the water heatingand for the heat exchanger element (23) there is additionally applied aheat conductive paste.
 16. Device for the regulated heating of media ina dental handpiece (1) having a) at least one media line (10) which canbe opened via a switch (32), b) a heating element (12, 31) associatedwith the media line (10), c) a temperature sensor (13, 34) detecting thetemperature of the medium and d) a regulation circuit (33) which isconnected with the temperature sensor (13, 34) and controls the heatingelement (12, 31) in dependence upon the sensor signals, characterized bya heat exchanger element (23) provided in the media line (11) which forthe return of the loss heat arising at the electronic components (22 a,46) of the regulation circuit (33) is thermally coupled therewith. 17.Dental spray handpiece for the delivery of air and/or water,characterized by a heating device for regulated heating of the media inaccordance with any of claims 1 to
 16. 18. Dental spray handpieceaccording to claim 17, characterized in that, the temperature sensor orsensors and the further electronic components of the heating device arearranged completely within the handpiece.